This chimney pipe partition thimble enables you to easily pass your chimney pipe through a wall for venting, while maintaining one inch of required clearance to combustibles. The thimble adjusts from 4 inches to 6 1/2 inches depending on the thickness of the wall it will pass through. It is 8.6875 inches in diameter and has been designed for use with Type B 6 inch round chimney pipe manufactured by Metal-Fab. This pipe partition thimble comes with a limited one-year warranty to ensure satisfaction.